Lubricant production process with product viscosity control

Abstract

High viscosity index, low pour point lubricants are produced by the oligomerization of a wax-derived lubricant fraction. The fraction may be produced from slack wax or de-oiled wax by hydroisomerization over zeolite beta or hydrocracking/isomerization over an amorphous catalyst followed by selective dewaxing, preferably by catalytic dewaxing over a highly shape selective zeolite such as ZSM-23. The preferred peroxides are ditertiary alkyl peroxides such as ditertiary butyl peroxide (DTBP) and are typically used at temperatures of 100 DEG -300 DEG C.

We claim: 
     
       1. A process for producing a 140 and higher V.I., low pour point lubricant from a deoiled slack wax feed containing 10 ppm nitrogen, and more than 0.01 wt% sulfur, the process comprising: (i) partially dewaxing the feed in an initial catalytic dewaxing step by contacting the feed under dewaxing conditions of elevated temperature and pressure in the presence of hydrogen with a dewaxing catalyst comprising zeolite beta and a hydrogenation-dehydrogenation component, to effect a partial removal of the waxy components by isomerization of the waxy paraffinic components to less waxy iso-paraffinic components, to produce a partially dewaxed effluent,   (ii) subjecting the partially dewaxed effluent to a selective dewaxing operation to effect a further removal of waxy components to produce a dewaxed lubricant fraction, and   (iii) subjecting the dewaxed lubricant fraction to treatment with an organic peroxide with an amount of organic peroxide equal to 1 to 50 wt% of the dewaxed lubricant fraction to increase the viscosity of the fraction.   
     
     
       2. A process according to claim 1 in which the peroxide comprises a ditertiaryalkyl peroxide. 
     
     
       3. A process according to claim 1 in which the peroxide comprises ditertiary butyl peroxide. 
     
     
       4. A process according to claim 1 in which the fraction is treated with the peroxide at a temperature of 100° to 300° C. 
     
     
       5. A process according to claim 1 in which the wax feed has a paraffin content of at least 70 weight percent. 
     
     
       6. A process according to claim 1 in which the zeolite beta has a silica:alumia ratio of at least 10.1. 
     
     
       7. A process according to claim 1 in which the zeolite beta has a silica:alumina ratio of at least 30.1. 
     
     
       8. A process according to claim 1 in which the selective dewaxing operation is a catalytic dewaxing over a dewaxing catalyst comprising zeolite ZSM-5. 
     
     
       9. A process according to claim 8 in which the dewaxing catalyst comprises a metal component having hydrogenation functionality and ZSM-5. 
     
     
       10. A process according to claim 9 in which the metal component is nickel. 
     
     
       11. A process according to claim 1 in which a fraction boiling below the lube boiling range is separated from the partially dewaxed effluent and subjected to treatment with an organic peroxide to bring its molecular weight into the lubricant range. 
     
     
       12. A process for producing a 140 and higher viscosity index lubricant from a deoiled slack wax feed which comprises: (i) subjecting the wax feed to hydrocracking/isomerization in the presence of a hydrocracking/isomerization catalyst comprising a hydrogenation-dehydrogenation component on a porous, acidic, amorphous carrier, to hydrocrack aromatics in the feed and isomerize waxy paraffins to form iso-paraffins,   (ii) subjecting the hydrocracked product to catalytic dewaxing over a ZSM-23 zeolite catalyst to produce a dewaxed lubricant fraction,   (iii) subjecting the dewaxed lubricant fraction to treatment with an organic peroxide compound to increase the viscosity of the fraction.   
     
     
       13. The process of claim 12 in which the peroxide comprises a ditertiaryalkyl peroxide. 
     
     
       14. The process of claim 12 in which the peroxide comprises a ditertiary butyl peroxide. 
     
     
       15. The process of claim 12 in which the peroxide treatment occurs at 100° to 300° C. 
     
     
       16. The process of claim 12 in which the amount of peroxide used to treat the fraction is from 1 to 50 weight percent of the fraction. 
     
     
       17. The process of claim 12 in which feed is a slack wax with a paraffin content of at least 70 weight percent. 
     
     
       18. A process for producing a lubricant having a V. I. of at least 140 and a pour point of -30° F. or lower from a deoiled slack wax wax feed comprising: (i) partially dewaxing the feed in an initial catalytic dewaxing step by contacting the feed under dewaxing conditions of elevated temperature and pressure in the presence of hydrogen with a dewaxing catalyst comprising zeolite beta and a hydrogenation-dehydrogenation component or a dewaxing catalyst comprising a hydrogenation-dehydrogenation component on an porous, acidic, amorphous carrier, to effect a partial removal of the waxy components by isomerization of the waxy paraffinic components to less waxy iso-paraffinic components, to produce a partially dewaxed effluent,   (ii) catalytically dewaxing the partially dewaxed effluent over an intermediate pore zeolite to effect a further removal of waxy components to produce a dewaxed lubricant fraction having a maximum pour point of -30° F., and   (iii) subjecting the dewaxed lubricant fraction to treatment with an organic peroxide with an amount of organic peroxide equal to 1 to 50 wt% of the dewaxed lubricant fraction to increase the viscosity of the fraction and produce a lubricant having a viscosity index of at least 140 and a maximum pour point of -30° F.   
     
     
       19. The process of claim 18 wherein the pour point of the high viscosity index lubricant is below -65° F.